Baker, a businessman and former state official, and Polito, a former state representative, announced last week that they would run as a team. A Boston Globe reporter then asked a campaign aide if Polito supports marriage equality, which has existed in Massachusetts for a decade, and the aide replied that she did. Polito had previously endorsed only civil unions for same-sex couples.

Now right-wing forces are pressing Polito “to dial back her new stance on the issue,” the Globereports, or else she and Baker could lose their support. Baker also backs marriage equality, and in his previous bid for governor, in 2010, he chose gay legislator Richard Tisei as his running mate.

In what the Globe calls an appeal “to both conservatives and moderates,” a campaign aide referred to marriage equality as a matter of settled law.

“Karyn supported civil unions at a time when most Republicans did not,” Baker campaign spokesman Tim Buckley told the paper. “Like many, including President Obama, Karyn’s position has evolved, and she now supports the existing law and will not work to undo the progress achieved over the last decade.” The campaign staff would not make Polito available for interviews on the matter.

So far, only one other candidate, businessman Mark Fisher, has announced plans to seek the Republican nomination for governor. He has sought the backing of social conservatives, the Globe notes.

Current governor Deval Patrick, a Democrat who is in his second term, has decided not to seek a third. Announced Democratic candidates include state attorney general Martha Coakley and physician Don Berwick. The primary election will be held September 9 and the general election November 4.